1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor package and a method of manufacturing a substrate for the semiconductor package. More particularly, the invention relates to a method of manufacturing a semiconductor package having a semiconductor chip mounted on a substrate and a method of manufacturing the substrate.
2. Description of the Related Art
Recently, there is a trend toward semiconductor packages having smaller thicknesses, and the trend is accompanied by similar requirements on semiconductor chips to be contained in such semiconductor packages, the requirements obviously including reductions in the thickness of such chips and improvements in the fineness of wirings and also including reductions in the thickness of substrates on which such semiconductors are to be mounted.
Proposed methods for providing a substrate having a small thickness include the use of a coreless substrate having no core layer as shown in FIG. 13. Electrode pads on a coreless substrate are formed to be coplanar with an insulation layer on a surface of the substrate, which results in various problems when flip-chip connections are made on the substrate.
For example, when there are flux residues between the electrode pads, leaks can be caused by the flux residues acting as paths of leakage in a practical environment of use. Let us assume that the substrate is poorly wetted when preliminary soldering is performed between the substrate and bumps on a semiconductor chip to make flip-chip connections and that the solder is pushed out of place during flip-chip connection. Then, bridging can occur between bumps adjacent to each other (see FIG. 14).
JP-A-2006-295114 (Patent Document 1) discloses a semiconductor package having a substrate on which an insulation layer is formed between each pair of electrode pads to insulate the electrode pads from each other. According to Patent Document 1, the substrate is formed as follows. An insulation layer is formed on a support plate, and etching is performed to form recesses on the insulation layer. Thereafter, plating is performed to form metal electrodes in the recesses, and the support plate is removed after forming the metal electrodes to leave an insulation layer between each pair of electrode pads.